Pressure switch



R. SHAW, JR

Get. 25, 1949'.

PRESSURE SWITCH Filed April 25, 1946 null- Ill LOAD :w /ENTOR mORNE-rPatented on. 25, 1949 PRESSURE SWITCH Richard Shaw, Jr., Bergenfleld, N.1., asaiznor to Bendix Aviation Corporation, Teterboro, N. J., acorporation of Delaware Application April 25, 1946, Serial No. 684,837

8 Claims. (Cl. 200-81) This invention relates to a switch arrangement,and more particularly to a switch which will be actuated atpredetermined values pressure by the operation of a pressure responsivemember.

An object of my present invention is to provide a switch which will beactuated upon operation of a pressure responsive member when thepressure acting upon said member reaches a predetermined value, andwhich will be restored to its initial condition when the actuatingpressure returns to a second predetermined value.

Another object of my invention is to provide a switch arrangement ofthe.character described in which the pressure value at which the switchis actuated may be readily adjusted to other predetermined pressurevalues.

A further object of the present invention is to provide a switcharrangement of the character I described in which the pressure value atwhich the switch is returned to initial condition after actuationthereof, may be readily adjusted to other predetermined pressure values.

Still a further object of my invention is to provide a switcharrangement of the character described in which the pressure lag incircuit operation may be varied.

Still another object of the invention is to provide a highly compact andrugged switch arrangement of the character described which shall beautomatic and positive in its operation, relatively inexpensive tomanufacture, which shall have a large variety of applications and yet bepractical and eflicient to a high degree in use.

Other objects of this invention will in part be obvious, and in parthereinafter pointed out.

The invention accordingly consists in the features of construction,combinations of elements and arrangement of parts which will beexemplifled in the construction hereinafter described, and of which thescope of application will be indicated in the appended claims.

In the accompanying drawings in which one of the various possibleillustrative embodiments of this invention is shown,

Figure 1 is a sideview, portions of which are in elevation, otherportions in cross section, or a switch arrangement embodying theinvention, while Figure 2 is a Wiring diagram showing the electricalconnections for said switch arrangement.

The switch arrangement herein provided comprises a solenoid adapted tobe energized upon actuation of a pair of control contacts by theexpansion and/or contraction of a pressure responsive member, oranerold. Energization oi the solenoid will actuate a second pair ofcontacts to control the operation or the electrical circuit in whichthey are connected.

The control contacts actuated by the anerold comprise a contact movableupon the expansion and/or contraction of the anerold due to pressurechanges, and a spring mounted contact adapted to be engaged by theanerold contact. The spring mounting of the second contact is such thatupon energization of the solenoid by the actuation of the controlcontacts, the movable core of the solenoid will increase the pressureupon the spring mounting. Thus, the control contacts may be held inengagement to maintain the solenoid energized even though the pressureaffecting the aneroid has changed sumciently to permit the opening ofthe closed contacts under normal conditions.

A pressure lag is thus provided which permits the switch arrangement tocontrol an electrical circuit between two predetermined pressures, thepressure at which the solenoid controlled contacts are actuated, and asecond predetermined pressure value at which the solenoid contactsreturn to their initial condition.

In the embodiment hereinafter described, the anerold upon expanding dueto a decrease in ambient pressure will close the control contacts toenergize the solenoid. The core of the solenoid will abut against thespring supporting one of the control contacts, increasing the pressureof the contacts. A further decrease in ambient pressure will not changethe condition of the closed contacts. However, upon an increase inambient pressure affecting the aneroid, the anerold will contract untila point is reached when the control contacts are opened. The pressure atwhich the control contacts will open will be a higher pressure than thatat which the contacts first closed. This is due to the bias of theresilient mounting by the solenoid core.

Referring now in detail to the drawings, Ill designates a switcharrangement embodying the present invention. The switch arrangementcomprises a support plate II in a sealed casing (not shown) having apressure connection through which the controlling pressure is applied tothe interior of the casing. Fixed to said plate in a suitable manner isa solenoid l2 comprising a core structure 13 and an armature It, saidcore being slidably received within a coil frame l5 supporting a coilIS. The upper end of the core I3 is provided with a pair of movablecontacts ll, resiliently mounted to said core as by spring l8 and cap l9and adapted to engage stationary contacts 31 upon energization of thecoil IS.

The lower end of said core I3 is provided with bottoming plates 20.Threaded into the lower end of the core I3 is a threaded rod 2|, thelower end of said rod extending through an aperture 22 in the mountingplate ll. Fixed to the lower end of the threaded rod 2i is a cap 23 madeof insulating material, the purposes of which will be more fullydescribed hereinafter. A return spring H abutting the bottoming plates20 and the upper surface of support H will return the core to theposition shown upon de-energization oi the coil l9.

Depending from the plate ii is a contact supporting block 25 made ofinsulation material. Fixed to said block, as by screws 26, is a leafspring 21 bent into U form, the upper portion 29 of which is adapted tobe engaged by the insulation cap 23. A control contact 29 is fixed tothe under side of the leaf spring 21 at its center and in line with thecore I3 and cap 23.

Fixed in a suitable manner beneath the platform II and within thecasing, is a pressure responsive member, or aneroid, 30. Fixed to thetop of said member, and insulated therefrom is an electrical contact 3|in alignment with and adapted to engage the electrical contact 29. Adecrease in pressure within the casing will cause the aneroid to expand,bringing the contact 3| into engagement with the spring mounted contact29. An increase in pressure will contract the aneroid to disengage thetwo contacts.

Referring now to Figure 2 of the drawings, the expansion of the pressureresponsive member 30 will cause the contact 3| to engage the contact 29.Closure of the contacts 29, 3| will energize the solenoid coil i6 by thefollowing circuit:

Through wire 32 connected to one side of a source of electrical energy45, wire 33, the contacts 29, 3| and wire 34, through coil l6, wire 35and thence through wire 36 connected to the other side of the source ofelectrical energy.

Energization of the solenoid l2 will cause an attraction of the armatureI4 moving the core |3 downwardly. Movement of the core l3 will cause themovable contacts resiliently mounted thereon to engage the stationarycontacts 31 associated therewith. Closure of the contacts ll, 31 willcomplete an electrical circuit through a load 38, herein shown in blockoutline, but which may be any piece of electrical equipment to becontrolled. The completed electrical circuit is through wire 32,contacts H, 31, wire 39, through the load 38, and thence through thewire 36.

The downward movement of the core l3 will cause the insulated cap 23 toabut against the upper portion 28 of the leaf spring 21 fiexing the samedownwardly toward the aneroid 30. The increase in bias of the spring 21will tend to maintain the contacts 29, 3| in engagement as the pressureresponsive member 30 contracts due to an increase in pressure. Thecontacts will become disengaged at a higher pressure than that at whichthe contacts first closed. There is thus provided a pressure lag betweenthe predetermined pressure value at which the load contacts are closedand at the predetermined pressure value at which the contacts againopen.

Means are now provided to adjust the pressure value at which the loadcontacts ll, 31 are first closed and the pressure value at which thewill open.

To this end, a threaded rod 40 is supported in the mounting plate H, thelower portion of said rod being provided with a cap 4| made ofinsulating material. The cap 4| is adapted to abut against the upperportion 28 of the leaf spring 21. The length of the threaded rod 40 maybe adjusted by means of a lock nut 42. The pressure upon the spring 21may be varied by loosening the nut 42 and rotating the rod 40 until theproper length is attained and then tightening the same in place by meansof the nut 42. The pressure upon the spring 21 will flex said springabout its support 25, increasing or decreasing the travel ing the locknut 24,

required 01' the contact 3| to engage the spring mounted contact 29.Thus, the pressure at which the contacts 29, 9| are engaged may bevaried to any desired predetermined value of pressure.

In furtherance of these ends, the length of threaded rod 2| may also beadjusted by means of a lock nut 24 threaded thereon, in a similarmanner. The rod 2| may be adjusted by loosenscrewing rod 2| until aproper length is attained, and then securing the rod by tightening thelock nut.

The travel of the solenoid core l3 being always the same, the degreewith which spring 21 is flexed upon energization of the solenoid willdepend upon the length of the rod 2|. The longer the length of the rod,the greater will be the bias of the spring, thus increasing the pressurevalue at which the control contacts will open. A greater pressure lagwill thus be obtained. A shorter length of rod 2| will bring thepressure value at which the contacts open closer to that at which thecontacts first close, thus decreasing the pressure lag obtained.

It will be apparent to those skilled in the art, that the pressureresponsive member 30 may be actuated by predetermined pressuredifferentials. The interior of said member instead of being evacuated,may be connected by an appropriate pressure line to one pressure source,while the exterior of said member subjected to another pressure source.In the use of the herein described pressure switch to control aircraftequipment, the interior of member 30 may be readily connected to thedynamic pressure line of a Pitot tube while the interior of the pressuretight casing in which the member is mounted may be connected to staticpressure line of the Pitot tube, or

vice versa.

Thus in the appended claims, the term predetermined pressure, or itsequivalent, will include the predetermined pressure afiecting anevacuated member 30, and the predetermined differential in pressures ofthe interior and exterior of said member.

It will thus be seen that there is provided a switch arrangement inwhich the various objects are attained and which is well adapted to meetthe requirements of practical use.

As various possible embodiments may be made of the invention set forthabove, and as various changes may be made in the embodiment illustrated,it is to be understood that all matter set forth herein or shown in theaccompanying drawings is to be interpreted as illustrative rather thanin a limiting sense.

Having thus described my invention, I claim as new and desire to secureby Letters Patent:

1. A pressure switch comprising, a pressure responsive member adapted toexpand and contract under varying pressures, a pair of contacts adaptedto be actuated by said member at a predetermined pressure value, asecond pair of contacts, means adapted to actuate said last contactsupon actuation of said first contacts, resilient means associated withsaid first contacts, and means included in-said actuating means to biassaid resilient means to hold said first contacts actuated until a secondpredetermined pressure afiects said member to restore said firstcontacts to their initial condition, whereupon said actuating means willrestore said second contacts to their initial condition.

2. A pressure switch comprising, a pressure responsive member adapted toexpand and contract under varying pressures, a pair of contacts adaptedto be actuated by said member at a predetermined pressure value, asecond pair of contacts, a solenoid adapted to be energized uponactuation of said first contacts to actuate said second contacts, andresilient means associated with said first contacts, said last meansbeing biased by the core of said solenoid upon energization thereof tohold said first contacts actuated until a second predetermined pressureaffects said member to restore said first contacts to their initialcondition to de-energize said solenoid.

3. A pressure switch comprising,a pressure responsive member adapted toexpand and contract under varying pressures, a pair of contacts adaptedto be actuated by said member at a predetermined pressure value, asecond pair of contacts, a solenoid adapted to be energized uponactuation of said first contacts to actuate said second contacts,resilient means associated with said first contacts, said last meansbeing biased by the core of said solenoid upon energization thereof tohold said first contacts actuated until a second predetermined pressureaffects said member to restore said first contacts to their initialcondition to de-energize said solenoid, and means for biasing saidresilient means to'adjust the pressure value at which said firstcontacts are actuated by said member.

4. A pressure switch comprising, a pressure responsive member adapted toexpand and contract under varying pressures, a pair of contacts adaptedto be actuated by said member at a predetermined pressure value, asecond pair of contacts, a solenoid adapted to be energized uponactuation of said first contacts to actuate said second contacts,resilient means associated with said first contacts, said last meansbeing biased by the core of said solenoid upon energization thereof tohold said first contacts actuated until a second predetermined pressureaffects said member to restore said first contacts to their initialcondition to de-energize said solenoid, means for biasing said resilientmeans to adjust the pressure value at which said first contacts areactuated by said member, and means associated with said solenoid forvarying the bias on said resilient means upon energization of saidsolenoid to adjust the pressure value at which said first contacts arerestored to initial condition.

5. A pressure switch comprising, a pressure responsive member adapted toexpand and contract under varying pressure values, a contact movabletherewith, a second contact adapted to be engaged by said first contactupon expansion of said member when a predetermined pressure affects saidmember, a resilient mounting for said second contact, a solenoid adaptedto be energized upon engagement of said first and second contacts, amember on the core of said solenoid adapted to bias said resilient meansupon energization of said solenoid to hold said first and secondcontacts engaged until a second predetermined pressure contracts saidmember to disengage said first contact from said second contact. and aset of contacts adapted to be closed upon energization of said solenoid.

6. A pressure switch comprising, a pressure responsive member adapted toexpand and contract under varying pressure values, a contact secondcontact, a solenoid adapted to be energized upon engagement of saidfirst and second contacts, a member on the core of said solenoid adaptedto bias said resilient means upon energization of said solenoid to holdsaid first and second contacts engaged until a second predeterminedpressure contracts said member to disen gage said first contact fromsaid second contact, a set of contacts adapted to be closed uponenergization of said solenoid, and means for biasing said resilientmeans to vary the distance of travel of said first contact to adjust thepressure at which said first and second contacts are engaged.

"I. A pressure switch comprising, a pressure responsive member adaptedto expand and con-- gage said first contact from said second contact,

a set of contacts adapted to be closed upon ener-' gization of saidsolenoid, means for biasing said resilient means to vary the distance oftravel of said first contact to adjust the pressure at which said firstand second contacts are engaged, and means for adjusting the length ofsaid core member to vary the bias on said resilient means by said memberupon energization of said solenoid to adjust the pressure value at whichsaid first and second contacts are disengaged.

8. A pressure switch comprising, a pressure responsive member adapted toexpand and contract under varying pressures, a contact movabletherewith, a second contact adapted to be engaged by said first contactupon expansion of said memmovable therewith, a second contact adapted tobe engaged by said first contact upon expansion of said member when apredetermined pressure aflects said member. a resilient mounting torsaid ber when a predetermined pressure affects said member, a resilientmounting for said second contact, a rod adjustable in length abuttingsaid mounting for varying the pressure value at which said first contactengages said second contact, a solenoid adapted to be energized uponengagement of said first and second contacts, a rod adjustable in lengthon the core of said solenoid adapted to abut the resilient mounting ofsaid second contact to hold said first and second contacts engaged untila second pressure determined by the length of said second rod contractssaid member to disengage said first contact from said second contact,and a switch actuated upon the energization of said solenoid.

RICHARD SHAW, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

